Bubbles attenuate elastic waves at seismic frequencies: First experimental evidence

• Published in: Geophysical research letters Vol. 42; no. 10; pp. 3880 - 3887
• Main Authors: Tisato, Nicola, Quintal, Beatriz, Chapman, Samuel, Podladchikov, Yury, Burg, Jean-Pierre
• Format: Journal Article
• Language: English
• Published: Washington Blackwell Publishing Ltd 28.05.2015; John Wiley & Sons, Inc
• Subjects: Accumulation; Attenuation; Bearing; Biosphere; Bubbles; Carbon dioxide; Computational fluid dynamics; Computer simulation; Dissolution; Dissolving; Elastic waves; Eruptions; Explosions; exsolution-dissolution; Fluid flow; Fluids; Frequency dependence; gas bubbles; Gases; Hazard mitigation; Land mines; Mathematical models; Migration; Monitoring; Numerical models; P-waves; Reservoirs; Rock; Rocks; Seismic tomography; Seismic waves; Simulation; Sound waves; Surveying; Tomography; Wave attenuation; Wave propagation
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1002/2015GL063538

The migration of gases from deep to shallow reservoirs can cause damageable events. For instance, some gases can pollute the biosphere or trigger explosions and eruptions. Seismic tomography may be employed to map the accumulation of subsurface bubble‐bearing fluids to help mitigating such hazards. Nevertheless, how gas bubbles modify seismic waves is still unclear. We show that saturated rocks strongly attenuate seismic waves when gas bubbles occupy part of the pore space. Laboratory measurements of elastic wave attenuation at frequencies <100 Hz are modeled with a dynamic gas dissolution theory demonstrating that the observed frequency‐dependent attenuation is caused by wave‐induced‐gas‐exsolution‐dissolution (WIGED). This result is incorporated into a numerical model simulating the propagation of seismic waves in a subsurface domain containing CO2‐gas bubbles. This simulation shows that WIGED can significantly modify the wavefield and illustrates how accounting for this physical mechanism can potentially improve the monitoring and surveying of gas bubble‐bearing fluids in the subsurface. Key Points Gas bubbles in the fluid saturating a rock attenuate seismic waves (1/Q) Wave‐induced‐gas‐exsolution‐dissolution (WIGED) explains the increase of 1/Q WIGED can help detecting gas‐bearing fluids in the subsurface